1. Field of the Invention
The present invention relates to method and apparatus for forming images and more particularly to an image forming method and apparatus of the type in which an original image is provisionally transformed into a time series electric signal by photo-electric transformation and then the electric signal is transferred or processed to form a picture signal with which an image of the original is formed by employing a known technique such as laser beam modulation or CRT control.
2. Description of the Prior Art
In a known image forming process involving a data transfer or transmission step such as facsimile, an original is read using a photo-electric transducer such as solid image sensor to photo-electrically convert the original image into a time series electric signal. The electric signal thus provisionally formed is transferred to the station at which a final image of the original is formed using the electric signal. In this process it is a common practice of the prior art to detect only the difference in density of the original but not the difference in color thereof.
However, there are sometimes such cases where the original document contains a differently colored figure or graph. In this case, it is impossible to distinguish one color from another by photo-electrically transformed signals as mentioned above. These signals contain only information of density level for all of the colors present in the original document. Since colors present in an original are generally of high density, two different colors in an original document are rendered in nearly equal density signals so that is is impossible to distinguish one from another in the reproduced original image. In general, the black portion of an original can be reproduced completely and faithfully in the reproduced image. However, the grey portion of the original and the differently colored figures or graphs contained in the same original are represented equally in grey in the reproduced image. Therefore, it is very difficult to distinguish one color from another on the reproduction.